Semiconductor structure and manufacturing method thereof

ABSTRACT

A semiconductor structure includes a first device and a second device. The first device includes a first substrate, a plurality of vias passing through the first substrate and filled with a conductive or semiconductive material and a first oxide layer surrounding the conductive or semiconductive material, a cavity surrounded by the first substrate, a metallic material disposed over the first surface, a second oxide layer disposed over the second surface, a membrane disposed over the second oxide layer and the cavity, a heater disposed within the membrane, a sensing electrode disposed over the membrane and the heater, and a sensing material disposed over the cavity and contacting with the sensing electrode. The second device includes a second substrate, and a bonding structure disposed over the second substrate. The metallic material is bonded with the bonding structure to integrate the first device with the second device.

BACKGROUND

Electronic equipment involving semiconductive devices are essential for many modern applications. The semiconductive device has experienced rapid growth. Technological advances in materials and design have produced generations of semiconductive devices where each generation has smaller and more complex circuits than the previous generation. In the course of advancement and innovation, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometric size (i.e., the smallest component that can be created using a fabrication process) has decreased. Such advances have increased the complexity of processing and manufacturing semiconductive devices.

Micro-electro mechanical system (MEMS) devices have been recently developed and are also commonly involved in electronic equipment. The MEMS device is micro-sized device, usually in a range from less than 1 micron to several millimeters in size. The MEMS device includes fabrication using semiconductive materials to form mechanical and electrical features. The MEMS device may include a number of elements (e.g., stationary or movable elements) for achieving electro-mechanical functionality. MEMS devices are widely used in various applications. MEMS applications include motion sensors, pressure sensors, printer nozzles, or the like. Other MEMS applications include inertial sensors, such as accelerometers for measuring linear acceleration and gyroscopes for measuring angular velocity. Moreover, MEMS applications are extended to optical applications, such as movable mirrors, and radio frequency (RF) applications, such as RF switches or the like.

As technologies evolve, design of the devices becomes more complicated in view of small dimension as a whole and increase of functionality and amounts of circuitries. The devices involve many complicated steps and increases complexity of manufacturing. The increase in complexity of manufacturing may cause deficiencies such as high yield loss, warpage, low signal to noise ratio (SNR), etc. Therefore, there is a continuous need to modify structure and manufacturing method of the devices in the electronic equipment in order to improve the device performance as well as reduce manufacturing cost and processing time.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic perspective view of a semiconductor structure in accordance with some embodiments of the present disclosure.

FIG. 2 is a schematic exploded view of a semiconductor structure of FIG. 1 in accordance with some embodiments of the present disclosure.

FIG. 3 is a schematic cross-sectional view of a semiconductor structure along AA′ of FIG. 1 in accordance with some embodiments of the present disclosure.

FIG. 4 is a schematic perspective view of a semiconductor structure in accordance with some embodiments of the present disclosure.

FIG. 5 is a schematic exploded view of a semiconductor structure of FIG. 4 in accordance with some embodiments of the present disclosure.

FIG. 6 is a schematic cross-sectional view of a semiconductor structure along BB′ of FIG. 4 in accordance with some embodiments of the present disclosure.

FIG. 7 is a schematic perspective view of a semiconductor structure in accordance with some embodiments of the present disclosure.

FIG. 8 is a schematic cross-sectional view of a semiconductor structure along CC′ of FIG. 7 in accordance with some embodiments of the present disclosure.

FIG. 9 is a flow diagram of a method of manufacturing a semiconductor structure in accordance with some embodiments of the present disclosure.

FIG. 9A is a cross-sectional view of a first substrate in accordance with some embodiments of the present disclosure.

FIG. 9B is a cross-sectional view of a first substrate with a first membrane layer in accordance with some embodiments of the present disclosure.

FIG. 9C is a cross-sectional view of a first substrate with a heater in accordance with some embodiments of the present disclosure.

FIG. 9D is a cross-sectional view of a first substrate with a second membrane layer in accordance with some embodiments of the present disclosure.

FIG. 9E is a cross-sectional view of a first substrate with a sensing electrode in accordance with some embodiments of the present disclosure.

FIG. 9F is a cross-sectional view of a first substrate with a sacrificial oxide in accordance with some embodiments of the present disclosure.

FIG. 9G is a cross-sectional view of a first substrate with a reduced thickness in accordance with some embodiments of the present disclosure.

FIG. 9H is a cross-sectional view of a first substrate with a metallic material in accordance with some embodiments of the present disclosure.

FIG. 9I is a cross-sectional view of a first substrate with a cavity in accordance with some embodiments of the present disclosure.

FIG. 9J is a cross-sectional view of a first substrate and a second substrate in accordance with some embodiments of the present disclosure.

FIG. 9K is a cross-sectional view of a first substrate bonded with a second substrate in accordance with some embodiments of the present disclosure.

FIG. 9L is a cross-sectional view of removal of a sacrificial oxide in accordance with some embodiments of the present disclosure.

FIG. 9M is a cross-sectional view of a semiconductor structure in accordance with some embodiments of the present disclosure.

FIG. 10 is a flow diagram of a method of manufacturing a semiconductor structure in accordance with some embodiments of the present disclosure.

FIG. 10A is a cross-sectional view of a first substrate in accordance with some embodiments of the present disclosure.

FIG. 10B is a cross-sectional view of a first substrate with a first membrane layer in accordance with some embodiments of the present disclosure.

FIG. 10C is a cross-sectional view of a first substrate with a heater in accordance with some embodiments of the present disclosure.

FIG. 10D is a cross-sectional view of a first substrate with a second membrane layer in accordance with some embodiments of the present disclosure.

FIG. 10E is a cross-sectional view of a first substrate with a sensing electrode in accordance with some embodiments of the present disclosure.

FIG. 10F is a cross-sectional view of a first substrate with a sacrificial oxide in accordance with some embodiments of the present disclosure.

FIG. 10G is a cross-sectional view of a first substrate with a reduced thickness in accordance with some embodiments of the present disclosure.

FIG. 10H is a cross-sectional view of a first substrate with a metallic material in accordance with some embodiments of the present disclosure.

FIG. 10I is a cross-sectional view of a first substrate with a cavity in accordance with some embodiments of the present disclosure.

FIG. 10J is a cross-sectional view of a first substrate and a second substrate in accordance with some embodiments of the present disclosure.

FIG. 10K is a cross-sectional view of a second substrate with an IMD layer in accordance with some embodiments of the present disclosure.

FIGS. 10L-1 and 10L-2 are cross-sectional views of a second substrate with an isolation layer in accordance with some embodiments of the present disclosure.

FIG. 10M is a cross-sectional view of a second substrate with a third oxide layer in accordance with some embodiments of the present disclosure.

FIG. 10N is a cross-sectional view of a second substrate with an interconnect structure in accordance with some embodiments of the present disclosure.

FIG. 10O is a cross-sectional view of a second substrate with a bonding structure in accordance with some embodiments of the present disclosure.

FIG. 10P is a cross-sectional view of a metallic material bonded with a bonding structure in accordance with some embodiments of the present disclosure.

FIG. 10Q is a cross-sectional view of removal of a sacrificial oxide in accordance with some embodiments of the present disclosure.

FIG. 10R is a cross-sectional view of a semiconductor structure in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

A sensor is an electronic equipment for detecting a present of a predetermined material such as a liquid, a gas or etc. The sensor can sense the present of the predetermined material by various suitable mechanisms such as electrochemical, electromechanical, optical or etc. The sensor can sense the predetermined material and generate an electrical signal accordingly for further processing. The sensor can involve a MEMS device for sensing the present of the predetermined material by electromechanical mechanism, and a complementary metal oxide semiconductor (CMOS) device for processing the electrical signal generated upon the detection of the present of the predetermined material. The MEMS device can integrate with the CMOS device by suitable operations such as wire bonding. Since the sensor involves the MEMS device and the CMOS device which are fabricated separately, a geometric size or a form factor of the sensor is undesirably large.

Furthermore, the sensor is required to be operated under a predetermined high operating temperature (for example, greater than 700° C.). The sensor includes a heater for providing the predetermined operating temperature for sensing the predetermined material. The heater is made of various materials such as tungsten. However, a heating efficiency of the heater made by tungsten is relatively low, and a power consumption of the heater is undesirably high.

In the present disclosure, a sensor with an improved semiconductor structure is disclosed. The semiconductor structure includes a MEMS device and a CMOS device. The MEMS device and the CMOS device are integrated by formation of vias and bonding operations. Several vias are formed in a MEMS substrate, and a metallic material is disposed over a surface of the MEMS substrate. The metallic material is configured to be bonded with a bonding structure disposed over the CMOS substrate. As such, the MEMS device is integrated with the CMOS device by the metallic material and the bonding structure. Such integration can reduce a form factor of the semiconductor structure and miniaturize the sensor. Furthermore, a performance of the sensor with the improved semiconductor structure is enhanced, such as low parasitic capacitance, low noise, high signal to noise ratio (SNR), high sensitivity and reactivity, etc.

In addition, the MEMS device in the semiconductor structure is configured to detect a present of a predetermined gas. The MEMS device includes a membrane, a heater, a sensing electrode and a sensing material. The sensing electrode can detect the predetermined gas and generate a corresponding electrical signal when the predetermined gas is present and reacted with the sensing material. The MEMS device is required to operate for detection of the predetermined gas under a predetermined temperature. The heater provides the predetermined temperature for the operation of the MEMS device. The heater includes tungsten alloy, tungsten silicide (WSi), titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl) or etc. Such heater has a high resistivity and thus provides a high heating efficiency during the operation of the MEMS device.

FIG. 1 is a schematic perspective view of a semiconductor structure in accordance with some embodiments of the present disclosure. The semiconductor structure includes a first device 100. The first device 100 includes a first substrate 101, an oxide 101 d, a cavity 102, a metallic material 103, a membrane 104, a heater 105, a sensing electrode 106 and a sensing material 107. FIG. 2 is a schematic exploded view of the first device 100, which illustrates the first substrate 101, the membrane 104 and the sensing material 107. The heater 105 is disposed inside the membrane 104. The sensing electrode 106 is partially covered by the sensing material 107. FIG. 3 is a schematic cross sectional view of the first device 100 along AA′ of FIG. 1.

In some embodiments, the first device 100 is configured to sense a present of a predetermined material such as a gas. In some embodiment, the first device 100 is configured to detect a present of a toxic and hazardous gas such as carbon monoxide, etc. In some embodiments, the first device 100 is a part of a sensor. In some embodiments, the first device 100 is a part of a gas sensor or a gas detector. In some embodiments, the first device 100 can generate an electrical signal when the predetermined material is present and detected. In some embodiments, the first device 100 is a MEMS device including electro-mechanical elements. In some embodiments, the first device 100 has a small form factor. In some embodiments, the first device 100 has a thickness of about less than about 100 um. In some embodiments, the first device 100 is configured to be disposed over and bonded with another substrate.

In some embodiments, the first device 100 includes the first substrate 101. In some embodiments, the first substrate 101 includes silicon, glass, ceramic or other suitable materials. In some embodiments, the first substrate 101 is a silicon substrate. In some embodiments, the first substrate 101 is a MEMS substrate. In some embodiments, the first substrate 101 includes electrical circuits formed on or in the first substrate 101. In some embodiments, the first substrate 101 includes transistors, capacitors, resistors, diodes, photo-diodes and/or the like. In some embodiments, the first substrate 101 has a thickness of about 20 um to about 500 um.

In some embodiments, the first substrate 101 includes a first surface 101 a, a second surface 101 b opposite to the first surface 101 a. In some embodiments, the first substrate 101 includes several vias 101 c passing through the first substrate 101. In some embodiments, each via 101 c is extended from the first surface 101 a to the second surface 101 b. In some embodiments, the vias 101 c are trenches. In some embodiments, there is a portion 101 f of the first substrate 101 surrounded by adjacent vias 101 c. The portion 101 f is disposed between two or more of the vias 101 c. In some embodiments, each via 101 c is filled with a conductive or semiconductive material 101 e. In some embodiments, the conductive or semiconductive material 101 e includes polysilicon. In some embodiments, the conductive or semiconductive material 101 e is isolated from the first substrate 101 by the first oxide layer 101 d-1. In some embodiments, the portion 101 f of the first substrate 101 is surrounded by the first oxide layer 101 d-1 and the conductive or semiconductive material 101 e.

In some embodiments, the first substrate 101 includes a first oxide layer 101 d-1 disposed within the first substrate 101. In some embodiments, the first oxide layer 101 d-1 is disposed conformal to the vias 101 c. In some embodiments, the first oxide layer 101 d-1 is disposed over a sidewall of the via 101 c. In some embodiments, the first oxide layer 101 d-1 surrounds the conductive or semiconductive material 101 e. In some embodiments, the first oxide layer 101 d-1 isolates the portion 101 f and the conductive or semiconductive material 101 e from a rest of the first substrate 101. In some embodiments, the first oxide layer 101 d-1 includes silicon oxide or any other suitable materials. In some embodiments, the first oxide layer 101 d-1 has a thickness of about 0.1 um to about 5 um.

In some embodiments, a second oxide layer 101 d-2 is disposed over the second surface 101 b of the first substrate 101 and the vias 101 c. In some embodiments, the second oxide layer 101 d-2 covers the second surface 101 b, a portion of the first oxide layer 101 d-1 and a portion of the conductive or semiconductive material 101 e. In some embodiments, the second oxide layer 101 d-2 has a thickness of about 0.1 um to about 5 um. In some embodiments, the second oxide layer 101 d-2 is configured to promote an adhesion with a structure or material disposed thereon.

In some embodiments, the second oxide layer 101 d-2 includes several first recesses 101 g. In some embodiments, the first recess 101 g exposes a part of the portion 101 f of the first substrate 101. In some embodiments, the portion 101 f of the first substrate 101 is not covered by the second oxide layer 101 d-2. In some embodiments, the second oxide layer 101 d-2 is coupled with the first oxide layer 101 d-1 and becomes the oxide 101 d. In some embodiments, the second oxide layer 101 d-2 includes same material as or different material from the first oxide layer 101 d-1. In some embodiments, the second oxide layer 101 d-2 includes silicon oxide or other suitable materials. In some embodiments, the thickness of the second oxide layer 101 d-2 is same or different from the thickness of the first oxide layer 101 d-1.

In some embodiments, the cavity 102 is disposed within the first substrate 101. In some embodiments, the cavity 102 is surrounded by the first substrate 101. In some embodiments, the cavity 102 passes through the first substrate 101 and the second oxide layer 101 d-2. In some embodiments, the cavity 102 extends through the first surface 101 a and the second surface 101 b of the first substrate 101. In some embodiments, the second oxide layer 101 d-2 is disposed over the cavity 102. The cavity 102 passes through the first substrate 101 but not the second oxide layer 101 d-2. In some embodiments, the cavity 102 is disposed at a central portion of the first substrate 101. In some embodiments, a cross section of the cavity 102 is in a rectangular, quadrilateral, triangular, circular, polygonal or other suitable shapes.

In some embodiments, the metallic material 103 is disposed over the first surface 101 a of the first substrate 101. In some embodiments, the metallic material 103 covers the portion 101 f of the first substrate 101 or the vias 101 c. In some embodiments, the metallic material 103 is electrically connected with the portion 101 f of the first substrate 101 or the conductive or semiconductive material 101 e. In some embodiments, the metallic material 103 includes copper, aluminum, aluminum copper alloy or other suitable materials. In some embodiments, the metallic material 103 is configured to electrically connect with a circuitry external to the first substrate 101. In some embodiments, the metallic material 103 is configured to receive a bonding structure.

In some embodiments, the membrane 104 is disposed over the second surface 101 b of the first substrate 101, the second oxide layer 101 d-2 and the cavity 102. In some embodiments, the membrane 104 is attached with the second oxide layer 101 d-2. In some embodiments, the membrane 104 includes several holes through the membrane 104. In some embodiments, the membrane 104 includes silicon, silicon dioxide, silicon nitride, silicon carbide, porous silicon, composite film or other suitable materials. In some embodiments, the membrane 104 has a low conductivity to minimize heat loss. The heat provided by the heater 105 would not be easily dissipated by the membrane 104. In some embodiments, the membrane 104 is in a rectangular, quadrilateral, triangular, circular, polygonal or any other suitable shapes. In some embodiments, the membrane 104 has a thickness of about 0.1 um to about 10 um.

In some embodiments, the heater 105 is disposed within the membrane 104. In some embodiments, the heater 105 includes single or multiple layers. The layers are disposed over each other. In some embodiments, the heater 105 includes tungsten alloy, tungsten silicide (WSi), titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), chromium (Cr), platinum (Pt), titanium nitride (TiN), molybdenum (Mo), polysilicon, silicon carbide (SiC), tantalum nitride (TaN), tantalum oxide (TaO) or other suitable materials. In some embodiments, the heater 105 has a width of about 0.1 um to about 25 um. In some embodiments, a melting point of the heater 105 is about 500° C.-3000° C. In some embodiments, a resistivity of the heater 105 is greater than about 6×10⁻⁸ ohm-meter (Ω·m).

In some embodiments, the heater 105 is configured to provide an operating temperature for sensing a predetermined material by the first device 100. A present of the predetermined material is sensed under the operating temperature. In some embodiments, the operating temperature is about 200° C. to about 800° C. In some embodiments, the operating temperature is greater than about 500° C. In some embodiments, a portion of the heater 105 is electrically connected to a power source, such that the heater 105 can provide the operating temperature when an electric current supplied from the power source passes through the heater 105.

In some embodiments, the heater 105 is laterally extended across the membrane 104. In some embodiments, the heater 105 is extended vertically along the membrane 104. In some embodiments, the heater 105 is in a zigzag configuration. In some embodiments, the heater 105 is extended over and across the cavity 102. In some embodiments, the heater 105 is electrically connected with the first substrate 101. In some embodiments, a portion of the heater 105 is electrically connected with the portion 101 f of the first substrate 101 through the first recess 101 g. In some embodiments, the portion of the heater 105 is extended from the membrane 104 to the portion 101 f of the first substrate 101 through the second oxide layer 101 d-2. As such, the portion of the heater 105 is surrounded by the membrane 104, the second oxide layer 101 d-2 and the portion 101 f of the first substrate 101.

In some embodiments, the sensing electrode 106 is disposed over the membrane 104 and the heater 105. In some embodiments, the sensing electrode 106 includes tungsten alloy, titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), titanium, titanium nitride (TiN), tantalum, tantalum nitride (TaN), tantalum oxide (TaO), tantalum silicon nitride (TaSiN), platinum (Pt) or other suitable materials. In some embodiments, the sensing electrode 106 is configured to sense a predetermined material such as a gas. When the predetermined material is present, the sensing electrode 106 would generate and transmit an electrical signal to the first substrate 101, other external substrate or other device for further processing. In some embodiments, the sensing electrode 106 has a width of about 0.1 um to about 25 um.

In some embodiments, the sensing electrode 106 is extended laterally or vertically over a surface of the membrane 104. In some embodiments, the sensing electrode 106 is laterally extended across the surface of the membrane 104. In some embodiments, the sensing electrode 106 is in a comb structure. In some embodiments, a portion of the sensing electrode 106 is coupled with the portion of the heater 105 through a third recess 104 b of the membrane 104. The portion of the sensing electrode 106 is extended through the third recess 104 b towards the heater 105.

In some embodiments, the sensing material 107 is disposed over the cavity 102 and contacts with the sensing electrode 106. In some embodiments, the sensing material 107 partially covers the sensing electrode 106, such that a portion of the sensing electrode 106 is encapsulated by the sensing material 107 while another portion of the sensing electrode 106 is extended out from the sensing material 107. In some embodiments, the sensing material includes tin dioxide (SnO₂), zine oxide (ZnO), indium oxide (In₂O₃) or other suitable materials.

In some embodiments, the sensing material 107 is configured to detect a predetermined material under the operating temperature. In some embodiment, a resistance of the sensing material 107 would change when the predetermined material is present and contacted with the sensing material 107. In some embodiments, the sensing electrode 106 is configured to sense a change of resistance of the sensing material 107. The resistance of the sensing material 107 is varied by a chemical reaction between the sensing material 107 and the predetermined material. The sensing material 107 would react with the predetermined material, resulting in a change of the resistance of the sensing material 107. For example, when the predetermined material such as carbon monoxide is present, the resistance of the sensing material 107 would be significantly dropped. The decrease of the resistance would initiate generation of an electrical signal from the sensing electrode 106. The electrical signal would transmit to the first substrate 101 or other substrate/device accordingly for further processing, such that the present of the predetermined material is detected. In some embodiments, when the predetermined material is present, an electrical signal would be generated and transmitted from the sensing electrode 106 to the metallic material 103 through the portion 101 f of the first substrate 101.

FIG. 4 is a schematic perspective view of a semiconductor structure 300 in accordance with some embodiments of the present disclosure. The semiconductor structure 300 includes a first device 100 and a second device 200. FIG. 5 is a schematic exploded view of the semiconductor structure 300. FIG. 6 is a schematic cross sectional view of the semiconductor structure 300 along BB′ of FIG. 4.

In some embodiments, the semiconductor structure 300 is configured for sensing a present of a predetermined material such as a gas. In some embodiments, the semiconductor structure 300 is a part of a sensor. In some embodiments, the semiconductor structure 300 is included in a gas sensor. In some embodiments, the semiconductor structure 300 is a monolithic sensor including the first device 100 integrated with the second device 200. In some embodiments, the semiconductor structure 300 includes the first device 100 which has similar configuration as the first device 100 described above or illustrated in any one of FIGS. 1-3.

In some embodiments, the semiconductor structure 300 includes the second device 200 disposed opposite to the first device 100. In some embodiments, the second device 200 is disposed under the first device 100. In some embodiments, the first device 100 is mounted on the second device 200. In some embodiments, the first device 100 is bonded with the second device 200, so that the first device 100 is integrated with the second device 200. In some embodiments, the second device 200 is a CMOS device including CMOS components.

In some embodiments, the second device 200 includes a second substrate 201 and a bonding structure 204 disposed over the second substrate 201. In some embodiments, the second substrate 201 includes CMOS components and circuitries disposed over or in the second substrate 201. In some embodiments, the second substrate 201 includes silicon or other suitable materials. In some embodiments, the second substrate 201 is a silicon substrate. In some embodiments, the second substrate 201 is a CMOS substrate. In some embodiments, the second substrate 201 includes a first surface 201 a and a second surface 201 b opposite to the first surface 201 a. In some embodiments, the first surface 201 a of the second substrate 201 is opposite to the first surface 101 a of the first substrate 101. In some embodiments, the second substrate 201 has a thickness of about 500 um to about 750 um.

In some embodiments, an intermetallic dielectric (IMD) layer 202 is disposed over the second substrate 201. In some embodiments, the IMD layer 202 includes oxide such as silicon oxide or other suitable materials. In some embodiments, the IMD layer 202 is disposed over the first surface 201 a of the second substrate 201. In some embodiments, an conductive structure 203 is disposed within the IMD layer 202. In some embodiments, the conductive structure 203 is electrically connected with the components or circuitries in the second substrate 201. In some embodiments, the conductive structure 203 includes tungsten, copper, aluminum, etc.

In some embodiments, the bonding structure 204 is disposed over the second substrate 201 and the IMD layer 202. In some embodiments, the bonding structure 204 is disposed over and electrically connected with the conductive structure 203. In some embodiments, the bonding structure 204 is configured to receive other conductive structure. In some embodiments, the bonding structure 204 includes germanium or other suitable materials. In some embodiments, the bonding structure 204 is extended over and across the IMD layer 202 or the first surface 201 a of the second substrate 201. In embodiments, the bonding structure 204 is a bond pad.

In some embodiments, the bonding structure 204 is electrically connected and bonded with the metallic material 103 to integrate and electrically connect the first device 100 with the second device 200. In some embodiments, the sensing electrode 106 is electrically connected with the conductive structure 203 or the second substrate 201 by the bonding structure 204 and the metallic material 103. In some embodiments, when the predetermined material is present, an electrical signal generated by a change of a resistance of the sensing material 107 is transmitted from the first device 100 to the second device 200 for further processing.

FIG. 7 is a schematic perspective view of a semiconductor structure 400 in accordance with some embodiments of the present disclosure. The semiconductor structure 400 includes a first device 100 and a second device 200. FIG. 8 is a schematic cross sectional view of the semiconductor structure 400 along CC′ of FIG. 7.

In some embodiments, the semiconductor structure 400 is configured for sensing a present of a predetermined material such as a gas. In some embodiments, the semiconductor structure 400 is a part of a sensor. In some embodiments, the semiconductor structure 400 is included in a gas sensor. In some embodiments, the semiconductor structure 400 is a monolithic sensor including the first device 100 integrated with the second device 200. In some embodiments, the semiconductor structure 400 includes the first device 100 which has similar configuration as the first device 100 described above or illustrated in any one of FIGS. 1-3. In some embodiments, the second device 200 includes a second substrate 201, an IMD layer 202, a conductive structure 203 and a bonding structure 204, which have similar configuration as described above or illustrated in any one of FIGS. 4-6.

In some embodiments, a dielectric layer 208 is disposed over the IMD layer 202. In some embodiments, the dielectric layer 208 includes oxide or other suitable dielectric materials. In some embodiments, the second device 200 includes an isolation layer 205 disposed over the CMOS substrate 201 and configured to thermally isolate the CMOS substrate 201 from the MEMS substrate 101. In some embodiments, the present of the isolation layer 205 increases a distance between the CMOS substrate 201 and the MEMS substrate 101 or a distance between the first device 100 and the second device 200, such that a heat provided by the heater 105 would not affect the CMOS substrate 201 or the second device 200. In some embodiments, the isolation layer 205 includes silicon or other suitable materials. In some embodiments, the isolation layer 205 is a silicon substrate or silicon wafer. In some embodiments, the isolation layer 205 includes dielectric material such as silicon oxide, silicon nitride, etc. In some embodiments, the isolation layer 205 is a passivation. In some embodiments, the isolation layer 205 has a thickness of about 30 um to about 300 um.

In some embodiments, the isolation layer 205 includes several fourth recesses 205 a disposed over the conductive structure 203. In some embodiments, the fourth recesses passes through the isolation layer 205 and the dielectric layer 208 to expose a portion of the conductive structure 203, such that the conductive structure 203 can electrically connect with external circuitry or components.

In some embodiments, a third oxide layer 207 is disposed over the isolation layer 205. In some embodiments, the third oxide layer 207 is disposed conformal to the fourth recesses 205. In some embodiments, the third oxide layer 207 includes silicon oxide or other suitable materials. In some embodiments, the third oxide layer 207 has a thickness of about 0.1 um to about 5 um.

In some embodiments, an interconnect structure 206 is disposed over the isolation layer 205, the third oxide layer 207 and the conductive structure 203. In some embodiments, the interconnect structure 206 includes conductive material such as aluminum, copper, etc. In some embodiments, the interconnect structure 206 is a redistribution layer (RDL).

In some embodiments, the interconnect structure 206 includes a via portion 206 a and an elongated portion 206 b. In some embodiments, the via portion 206 a passes through the isolation layer 205 and contacts with the conductive structure 203 or the IMD layer 202. In some embodiments, the via portion 206 a is extended from the isolation layer 205 to the IMD layer 202 and is disposed over the conductive structure 203. In some embodiments, the via portion 206 a is electrically connected with the conductive structure 203. In some embodiments, the via portion 206 a is conformal to the third oxide layer 207 disposed within the fourth recess 205 a. In some embodiments, the third oxide layer 207 is disposed between the via portion 206 a and the isolation layer 205.

In some embodiments, the interconnect structure 206 includes an elongated portion 206 b extending over and along the isolation layer 205. In some embodiments, the elongated portion 206 b is disposed over the third oxide layer 207. In some embodiments, the elongated portion 206 b is electrically connected with the conductive structure 203 through the via portion 206 a.

In some embodiments, the elongated portion 206 b is configured to receive the bonding structure 204. The bonding structure 204 is disposed over the elongated portion 206 b, so that the interconnect structure 206 is electrically connected with the bonding structure 204. In some embodiments, the CMOS substrate 201 and the MEMS substrate 101 are integrated by bonding the metallic material 103 with the bonding structure 204 and electrically connecting the CMOS substrate 201 with the MEMS substrate 101. In some embodiments, the elongated portion 206 b is bonded with the bonding structure 204, and the bonding structure 204 is bonded with the metallic material 103. Thus, the first device 100 is bonded and integrated with the second device 200 by the metallic structure 103, the bonding structure 204 and the elongated portion 206 b.

In the present disclosure, a method of manufacturing a semiconductor structure is also disclosed. In some embodiments, a semiconductor structure is formed by a method 500. The method 500 includes a number of operations and the description and illustration are not deemed as a limitation as the sequence of the operations.

FIG. 9 is an embodiment of a method 500 of manufacturing a semiconductor structure. The method 500 includes a number of operations (501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 512 and 513).

In operation 501, a first substrate 101 is received or provided as shown in FIG. 9A. In some embodiments, the first substrate 101 includes silicon, glass, ceramic or other suitable materials. In some embodiments, the first substrate 101 is a silicon substrate. In some embodiments, the first substrate 101 includes electrical circuits formed on or in the first substrate 101. In some embodiments, the first substrate 101 includes a first surface 101 a and a second surface 101 b opposite to the first surface 101 a. In some embodiments, the first surface 101 a is a back side of the first substrate 101, while the second surface 101 b is a front side of the first substrate 101.

In some embodiments, the first substrate 101 includes several vias 101 c extending from the second surface 101 b towards the first surface 101 a. In some embodiments, the vias 101 c are formed by photolithography and etching operations. In some embodiments, a first oxide layer 101 d-1 is disposed conformal to the vias 101 c. In some embodiments, the first oxide layer 101 d-1 is formed within the vias 101 c by thermal oxidation operations.

In some embodiments, each via 101 c is filled by a conductive or semiconductive material 101 e. In some embodiments, the conductive or semiconductive material 101 e includes polysilicon. The first oxide layer 101 d-1 is disposed between the first substrate 101 and the conductive or semiconductive material 101 e. In some embodiments, the conductive or semiconductive material 101 e is formed by deposition operations such as chemical vapor deposition (CVD), low pressure CVD (LPCVD), etc. In some embodiments, the conductive or semiconductive material 101 e is polished or planarized by suitable operations such as chemical mechanical planarization (CMP).

In some embodiments, a second oxide layer 101 d-2 is disposed over the first surface 101 a or the second surface 101 b of the first substrate 101. In some embodiments, the second oxide layer 101 d-2 is disposed over the vias 101 c and contacts with the first oxide layer 101 d-1 and the conductive or semiconductive material 101 e. In some embodiments, the second oxide layer 101 d-2 is formed by thermal oxidation operations. In some embodiments, the second oxide layer 101 d-2 is same material as or different material from the first oxide layer 101 d-1.

In operation 502, a first membrane layer 104-1 is disposed and patterned over the second oxide layer 101 d-2 as shown in FIG. 9B. In some embodiments, the first membrane layer 104-1 is disposed over the second oxide layer 101 d-2, and then patterned to form several second recesses 104 a. In some embodiments, the first membrane layer 104-1 is also disposed over the first surface 101 a of the first substrate 101. In some embodiments, the first membrane layer 104-1 includes silicon, silicon dioxide, silicon nitride, silicon carbide, porous silicon, composite film or other suitable materials. In some embodiments, the first membrane layer 104-1 is disposed by CVD or other suitable operations.

In some embodiments, the second recesses 104 a are formed by removing some of the first membrane layer 104-1 disposed between the vias 101 c. In some embodiments, the first membrane layer 104-1 is patterned to form the second recesses 104 a by photolithography and etching operations. In some embodiments, some of the second oxide layer 101 d-2 disposed under the second recesses 104 a are also removed to form several first recesses 101 g, and thus the first recesses 101 g are coupled with the second recesses 104 a respectively. In some embodiments, the first recess 101 g passes through the second oxide layer 101 d-2 and extends to the second surface 101 b of the first substrate 101.

In operation 503, a heater 105 is disposed and patterned over the first membrane layer 104-1 as shown in FIG. 9C. In some embodiments, the heater 105 is disposed over the second oxide layer 101 d-2, and then patterned by photolithography and etching operations. In some embodiments, the heater 105 is disposed over the second oxide layer 101 d-2 and within the first recesses 101 g and the second recesses 104 a. In some embodiments, the heater 105 is electrically connected with a portion 101 f of the first substrate 101 disposed between the vias 101 c. In some embodiments, the heater 105 includes tungsten alloy, tungsten silicide (WSi) titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), chromium (Cr), platinum (Pt), titanium nitride (TiN), molybdenum (Mo), polysilicon, silicon carbide (SiC), tantalum nitride (TaN), tantalum oxide (TaO) or other suitable materials.

In operation 504, a second membrane layer 104-2 is disposed and patterned over the heater 105 and the first membrane layer 104-1 as shown in FIG. 9D. In some embodiments, the second membrane layer 104-2 is disposed over the first membrane layer 104-1, and then patterned to form several third recesses 104 b. In some embodiments, the second membrane layer 104-2 is also disposed over the first surface 101 a of the first substrate 101. In some embodiments, the second membrane layer 104-2 includes silicon, silicon dioxide, silicon nitride, silicon carbide, porous silicon, composite film or other suitable materials. In some embodiments, the second membrane layer 104-2 includes same material as or different material from the first membrane layer 104-1. In some embodiments, the second membrane layer 104-2 is disposed by CVD or other suitable operations. In some embodiments, the first membrane layer 104-1 and the second membrane layer 104-2 become a membrane 104. The heater 105 is disposed within the membrane 104.

In some embodiments, the third recesses 104 b are formed by removing some of the second membrane layer 104-2 disposed over the second recesses 104 a. In some embodiments, the second membrane layer 104-2 is patterned to form the third recesses 104 b by photolithography and etching operations. In some embodiments, the third recess 104 b extends towards the heater 105 disposed within the second recess 104 a.

In operation 505, a sensing electrode 106 is disposed over the second membrane layer 104-2 as shown in FIG. 9E. In some embodiments, the sensing electrode 106 is disposed over the second membrane layer 104-2 and within the third recesses 104 b. In some embodiments, the sensing electrode 106 is disposed over the heater 105. In some embodiments, a portion of the sensing electrode 106 is coupled with a portion of the heater 105 through the third recess 104 b. In some embodiments, the sensing electrode 106 is patterned by photolithography and etching operations. In some embodiments, the sensing electrode 106 is configured to sense a predetermined material such as a gas. In some embodiments, the sensing electrode 106 includes tungsten alloy, titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), titanium, titanium nitride (TiN), tantalum, tantalum nitride (TaN), tantalum oxide (TaO), tantalum silicon nitride (TaSiN), platinum (Pt), or other suitable materials.

In operation 506, a sacrificial oxide 108 is disposed over the sensing electrode 106 and the second membrane layer 104-2 as shown in FIG. 9F. In some embodiments, the sacrificial oxide 108 covers the sensing electrode 106 and the second membrane layer 104-2 for protection. In some embodiments, the sacrificial oxide 108 is deposited by suitable operations such as CVD. In some embodiments, the sacrificial oxide 108 is polished and planarized by suitable operations such as chemical mechanical planarization (CMP).

In operation 507, some of the first substrate 101 are removed from the first surface 101 a to expose the conductive or semiconductive material 101 e as shown in FIG. 9G. In some embodiments, some of the first substrate 101, the second oxide layer 101 d-2, the first membrane layer 104-1 and the second membrane layer 104-2 disposed over the first surface 101 a are removed by suitable operations such as grinding, etching, etc. In some embodiments, the removal of some of the first surface 101 a is backside grinding operations. In some embodiments, some of the first substrate 101 are removed by grinding the first surface 101 a towards the second surface 101 b. In some embodiments, a thickness of the first substrate 101 is reduced by grinding over the first surface 101 a, such that a new first surface 101 a′ is formed and the conductive or semiconductive material 101 e is exposed.

In operation 508, a metallic material 103 is disposed over the new first surface 101 a′ and the vias 101 c as shown in FIG. 9H. In some embodiments, the metallic material 103 is disposed and then patterned by photolithography and etching operations, such that the metallic material 103 is formed over the portion 101 f of the first substrate 101 and the vias 101 c. In some embodiments, the metallic material 103 is disposed by electroplating, sputtering or other suitable operations. In some embodiments, the first substrate 101 is flipped before formation of the metallic material 103. In some embodiments, the metallic material 103 is configured to electrically connect with a circuitry external to the first substrate 101. In some embodiments, the metallic material 103 is configured to receive a bonding structure. In some embodiments, the metallic material 103 includes copper, aluminum, aluminum copper alloy or other suitable materials.

In operation 509, a cavity 102 is formed as shown in FIG. 9I. In some embodiments, some of the first substrate 101 are removed to form the cavity 102 by photolithography and etching operations. In some embodiments, some of the first substrate 101 are etched from the new first surface 101 a′ through the second surface 101 b to expose the first membrane layer 104-1 or the second oxide layer 101 d-2. In some embodiments, some of the first substrate 101 are etched until reaching the second oxide layer 101 d-2. In some embodiments, some of the first substrate 101 and some of the second oxide layer 101 d-2 are removed to form the cavity 102.

In operation 510, a second substrate 201 is received or provided as shown in FIG. 9J. In some embodiments, the second substrate 201 includes a first surface 201 a and a second surface 201 b opposite to the first surface 201 a. In some embodiments, the second substrate 201 includes CMOS components and circuitries disposed over or in the second substrate 201. In some embodiments, the second substrate 201 includes silicon or other suitable materials. In some embodiments, the second substrate 201 is a silicon substrate. In some embodiments, the second substrate 201 includes a bonding structure 204 disposed over the second substrate 201. In some embodiments, the bonding structure 204 is configured to receive the metallic material 103. In some embodiments, an IMD layer 202 is disposed over the second substrate 201, and a conductive structure 203 is disposed within the IMD layer 202. In some embodiments, the conductive structure 203 is disposed under and is electrically connected with the bonding structure 204.

In operation 511, the bonding structure 204 and the metallic material 103 are bonded as shown in FIG. 9K. In some embodiments, the first substrate 101 is disposed over the second substrate 201, and then the metallic material 103 is disposed and bonded with the bonding structure 204. In some embodiments, the metallic material 103 is bonded with the bonding structure 204 by eutectic bonding operations. In some embodiments, the bonding structure 204 includes germanium, and the metallic material 103 includes aluminum.

In operation 512, the sacrificial oxide 108 is removed as shown in FIG. 9L. In some embodiments, the sacrificial oxide 108 is removed to expose the sensing electrode 106 by etching operations such as wet etching or other suitable operations.

In operation 513, a sensing material 107 is disposed over the sensing electrode 106 as shown in FIG. 9M. In some embodiments, the sensing material 107 is disposed over the cavity 102 and contacts with the sensing electrode 106. In some embodiments, the sensing material 107 partially covers the sensing electrode 106, such that a portion of the sensing electrode 106 is encapsulated by the sensing material 107 while another portion of the sensing electrode 106 is extended out from the sensing material 107 and is not covered by the sensing material 107. In some embodiments, the sensing material includes tin dioxide (SnO₂), zine oxide (ZnO), indium oxide (In₂O₃) or other suitable materials.

In some embodiments, a semiconductor structure 300 including a first device 100 and second device 200 is formed. The semiconductor structure 300, the first device 100 and the second device 200 have similar configuration as in any one of FIGS. 1-6. In some embodiments, the sensing material 107 is configured to detect a predetermined material under the operating temperature. In some embodiment, a resistance of the sensing material 107 would change when the predetermined material is present and contacted with the sensing material 107. The resistance of the sensing material 107 is varied by a chemical reaction between the sensing material 107 and the predetermined material. The change of the resistance of the sensing material 107 is sensed by the sensing electrode 106.

FIG. 10 is an embodiment of a method 600 of manufacturing a monolithic sensor. The method 600 includes a number of operations (601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617 and 618).

In operation 601, a first substrate 101 is received or provided as shown in FIG. 10A. The operation 601 is similar to the operation 501 in FIG. 9A. In operation 602, a first membrane layer 104-1 is disposed and patterned as shown in FIG. 10B. The operation 602 is similar to the operation 502 in FIG. 9B. In operation 603, a heater 105 is disposed and patterned as shown in FIG. 10C. The operation 603 is similar to the operation 503 in FIG. 9C. In operation 604, a second membrane layer 104-2 is disposed and patterned as shown in FIG. 10D. The operation 604 is similar to the operation 504 in FIG. 9D. In operation 605, a sensing electrode 106 is disposed as shown in FIG. 10E. The operation 605 is similar to the operation 505 in FIG. 9E. In operation 606, a sacrificial oxide 108 is disposed and patterned as shown in FIG. 10F. The operation 606 is similar to the operation 506 in FIG. 9F. In operation 607, some of the first substrate 101 are removed as shown in FIG. 10G. The operation 607 is similar to the operation 507 in FIG. 9G. In operation 608, a metallic material 103 is disposed as shown in FIG. 10H. The operation 608 is similar to the operation 508 in FIG. 9H. In operation 609, a cavity 102 is formed as shown in FIG. 10I. The operation 609 is similar to the operation 509 in FIG. 9I.

In operation 610, a second substrate 201 is received or provided as shown in FIG. 10J. In some embodiments, the second substrate 201 includes a first surface 201 a and a second surface 201 b opposite to the first surface 201 a. In some embodiments, the second substrate 201 includes CMOS components and circuitries disposed over or in the second substrate 201. In some embodiments, the second substrate 201 includes silicon or other suitable materials. In some embodiments, the second substrate 201 is a silicon substrate.

In operation 611, an IMD layer 202 is formed over the second substrate 201 as shown in FIG. 10K. In some embodiments, the IMD layer 202 includes oxide such as silicon oxide or other suitable materials. In some embodiments, the IMD layer 202 is disposed over the first surface 201 a of the second substrate 201. In some embodiments, an conductive structure 203 is disposed within the IMD layer 202. In some embodiments, the conductive structure 203 is electrically connected with the components or circuitries in the second substrate 201. In some embodiments, the conductive structure 203 includes tungsten, copper, aluminum, etc. In some embodiments, a dielectric layer 208 is disposed over the IMD layer 202. In some embodiments, the dielectric layer 208 includes oxide or other suitable dielectric materials.

In operation 612, an isolation layer 205 is disposed and patterned as shown in FIGS. 10L-1 and 10L-2. In some embodiments, the isolation layer 205 is disposed over the second substrate 201. In some embodiments, the isolation layer 205 is attached to the IMD layer 202 by bonding operations. In some embodiments, the isolation layer 205 is a silicon substrate or silicon wafer. In some embodiments, the isolation layer 205 is bonded over the second substrate 201 by wafer bonding operations. In some embodiments, the isolation layer 205 includes dielectric material such as silicon oxide, silicon nitride, etc. In some embodiments, the isolation layer 205 is a passivation. In some embodiments, the isolation layer 205 is disposed by CVD or other suitable operations. In some embodiments, the dielectric layer 208 is patterned by removing some of the dielectric layer 208 disposed over the conductive structure 203. In some embodiments, the isolation layer 205 is patterned by removing some of the isolation layer 205 disposed over the conductive structure 203. In some embodiments, some of the isolation layer 205 are removed by photolithography and etching operations. As such, several fourth recesses 205 a are formed after patterning the isolation layer 205 and the dielectric layer 208. In some embodiments, some of the isolation layer 205 are removed so as to reduce a thickness of the isolation layer 205. In some embodiments, the thickness of the isolation layer 205 is reduced from about 700 um to about 30 um-300 um after bonding over the second substrate 201.

In operation 613, a third oxide layer 207 is disposed as shown in FIG. 10M. In some embodiments, the third oxide layer 207 is disposed conformal to the isolation layer 205. In some embodiments, the third oxide layer 207 is disposed conformal to the fourth recesses 205 a. In some embodiments, some of the third oxide layer 207 are disposed over the conductive structure 203, and then are removed to expose the conductive structure 203 by etching or other suitable operations. In some embodiments, the third oxide layer 207 includes silicon oxide or other suitable materials. In some embodiments, the third oxide layer 207 is disposed by CVD or other suitable operations.

In operation 614, an interconnect structure 206 is formed as shown in FIG. 10N. In some embodiments, the interconnect structure 206 is formed including formation of an via portion 206 a and an elongated portion 206 b. In some embodiments, the interconnect structure 206 is formed by electroplating, sputtering or other suitable operations. In some embodiments, the interconnect structure 206 includes conductive material such as aluminum, copper, etc. In some embodiments, the interconnect structure 206 is a redistribution layer (RDL).

In some embodiments, the via portion 206 a contacts with the IMD layer 202. In some embodiments, the via portion 206 a is disposed within the fourth recess 205 a and electrically coupled with the conductive structure 203. In some embodiments, the elongated portion 206 b is disposed along the third oxide layer 207. In some embodiments, the elongated portion 206 b is electrically connected with the conductive structure 203 through the via portion 206 a.

In operation 615, a bonding structure 204 is disposed over the elongated portion 206 b of the interconnect structure 206 as shown in FIG. 10O. In some embodiments, the elongated portion 206 b is configured to receive the bonding structure 204. The bonding structure 204 is disposed over the elongated portion 206 b, so that the interconnect structure 206 is electrically connected with the bonding structure 204. In some embodiments, the bonding structure 204 is disposed by electroplating, sputtering or other suitable operations. In some embodiments, the bonding structure 204 includes germanium.

In operation 616, the metallic material 103 is bonded with the bonding structure 204 as shown in FIG. 10P. The operation 616 is similar to the operation 511 in FIG. 9K. In operation 617, the sacrificial oxide 108 is removed as shown in FIG. 10Q. The operation 617 is similar to the operation 512 in FIG. 9L. In operation 618, a sensing material 107 is disposed as shown in FIG. 10R. The operation 618 is similar to the operation 513 in FIG. 9M. In some embodiments, a semiconductor structure 400 including a first device 100 and second device 200 is formed. The semiconductor structure 400, the first device 100 and the second device 200 have similar configuration as in any one of FIGS. 7-8.

In the present disclosure, an improved semiconductor structure is disclosed. The semiconductor structure includes a MEMS device integrated with a CMOS device by formation of vias and bonding operations. Several vias are formed in a MEMS substrate, and a metallic material is disposed over a surface of the MEMS substrate. The metallic material is configured to be bonded with a bonding structure disposed over the CMOS substrate. As such, the MEMS device is integrated with the CMOS device by the metallic material and the bonding structure. Such integration can reduce a form factor of the semiconductor structure and enhance a performance of the semiconductor structure.

In some embodiments, a semiconductor structure includes a first device and a second device. The first device includes a first substrate including a first surface, a second surface opposite to the first surface, and a plurality of vias passing through the first substrate and filled with a conductive or semiconductive material and a first oxide layer surrounding the conductive or semiconductive material, a cavity surrounded by the first substrate, a metallic material disposed over the first surface, covering some of the plurality of vias, and electrically connecting with the first substrate, a second oxide layer disposed over the second surface, a membrane disposed over the second oxide layer and the cavity, a heater disposed within the membrane and electrically connected with the first substrate through the oxide layer, a sensing electrode disposed over the membrane and the heater, and a sensing material disposed over the cavity and contacting with the sensing electrode. The second device includes a second substrate, and a bonding structure disposed over the second substrate, wherein the metallic material is bonded with the bonding structure to integrate the first device with the second device.

In some embodiments, the heater includes tungsten alloy, tungsten silicide (WSi), titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), chromium (Cr), platinum (Pt), titanium nitride (TiN), molybdenum (Mo), polysilicon, silicon carbide (SiC), tantalum nitride (TaN) or tantalum oxide (TaO). In some embodiments, the metallic material includes aluminum or copper, or the bonding structure includes germanium. In some embodiments, a portion of the first substrate is surrounded by the first oxide layer and the conductive or semiconductive material, and the conductive or semiconductive material is isolated from the first substrate by the first oxide layer. In some embodiments, the sensing electrode is configured to sense a change of resistance of the sensing material, and the resistance of the sensing material is varied by a chemical reaction between the sensing material and a predetermined material. In some embodiments, the heater is extended laterally or vertically along the membrane, or the sensing electrode is extended laterally or vertically over a surface of the membrane. In some embodiments, the conductive or semiconductive material includes polysilicon. In some embodiments, the membrane includes silicon, silicon dioxide (SiO₂) or silicon nitride (SiN), silicon carbide (SiC), porous silicon or composite film. In some embodiments, the sensing electrode includes tungsten alloy, titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), titanium, titanium nitride (TiN), tantalum, tantalum nitride (TaN), tantalum oxide (TaO), platinum (Pt) or tantalum silicon nitride (TaSiN). In some embodiments, the sensing material includes tin dioxide (SnO₂), zine oxide (ZnO) or indium oxide (In₂O₃).

In some embodiments, a semiconductor structure includes a CMOS substrate, an intermetallic dielectric (IMD) layer disposed over the CMOS substrate, a bonding structure disposed over the IMD layer, a MEMS substrate including a first surface facing the CMOS substrate and a second surface opposite to the first surface, a metallic material disposed over the first surface, a cavity surrounded by the MEMS substrate, a polysilicon disposed within the MEMS substrate, a first oxide layer disposed between the polysilicon and the MEMS substrate, a second oxide layer disposed over the second surface, a membrane disposed over the second oxide layer and the cavity, a heater disposed within the membrane and electrically connected with the MEMS substrate, sensing electrode disposed over the membrane and the heater, and electrically connected with the MEMS substrate, and a sensing material covering a portion of the sensing electrode, wherein the CMOS substrate and the MEMS substrate are integrated by bonding the metallic material with the bonding structure and electrically connecting the CMOS substrate with the MEMS substrate.

In some embodiments, the semiconductor structure further includes an isolation layer disposed over the CMOS substrate and configured to thermally isolate the CMOS substrate from the MEMS substrate, or an interconnect structure including a via portion passing through the isolation layer and contacted with the IMD layer, and an elongated portion extending over and along the isolation layer and configured to receive the bonding structure, or a third oxide layer disposed over the isolation layer and between the via portion and the isolation layer. In some embodiments, the bonding structure is a bond pad. In some embodiments, the second oxide layer is disposed over the cavity. In some embodiments, the heater is configured to provide an operating temperature of about 300° C. to about 800° C. to facilitate sensation of a predetermined gas by the sensing electrode, or the heater has a width of about 0.1 um to about 30 um.

In some embodiments, a method of manufacturing a semiconductor structure includes receiving a first substrate including a first surface, a second surface opposite to the first surface, a plurality of vias extending from the second surface towards the first surface and filled with a conductive or semiconductive material, a first oxide layer disposed between the first substrate and the conductive or semiconductive material, and a second oxide layer disposed over the second surface, disposing and patterning a first membrane layer over the second oxide layer, disposing and patterning a heater over the first membrane layer, disposing and patterning a second membrane layer over the heater and the first membrane layer, disposing a sensing electrode over the second membrane layer, disposing a sacrificial oxide over the sensing electrode and the second membrane layer, removing some of the first substrate from the first surface to expose the conductive or semiconductive material, disposing a metallic material over the first surface and the plurality of vias, forming a cavity surrounded by the first substrate, receiving a second substrate including a bonding structure disposed over the second substrate, bonding the metallic material with the bonding structure, removing the sacrificial oxide, and disposing a sensing material over the sensing electrode.

In some embodiments, the forming the cavity includes etching the first substrate from the first surface to expose the first membrane layer or the second oxide layer. In some embodiments, the bonding the metallic material with the bonding structure includes eutectic bonding operations. In some embodiments, the removing some of the first substrate includes grinding the first surface towards the second surface. In some embodiments, the method further includes forming an intermetallic dielectric (IMD) layer over the second substrate, disposing and patterning an isolation layer over the second substrate, disposing a third oxide layer conformal to the isolation layer, forming an interconnect structure including a via portion contacting with the IMD layer, and an elongated portion disposed along the third oxide layer and coupled with the bonding structure.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

The invention claimed is:
 1. A semiconductor structure, comprising: a first device comprising: a first substrate including a first surface, a second surface opposite to the first surface, and a plurality of vias passing through the first substrate and filled with a conductive or semiconductive material and a first oxide layer surrounding the conductive or semiconductive material; a cavity surrounded by the first substrate; a metallic material disposed over the first surface, covering some of the plurality of vias, and electrically connecting with the first substrate; a second oxide layer disposed over the second surface; a membrane disposed over the second oxide layer and the cavity; a heater disposed within the membrane and electrically connected with the first substrate through the oxide layer; a sensing electrode disposed over the membrane and the heater; and a sensing material disposed over the cavity and contacting with the sensing electrode, and a second device comprising: a second substrate; and a bonding structure disposed over the second substrate, wherein the metallic material is bonded with the bonding structure to integrate the first device with the second device.
 2. The semiconductor structure of claim 1, wherein the heater includes tungsten alloy, tungsten silicide (WSi), titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), chromium (Cr), platinum (Pt), titanium nitride (TiN), molybdenum (Mo), polysilicon, silicon carbide (SiC), tantalum nitride (TaN) or tantalum oxide (TaO).
 3. The semiconductor structure of claim 1, wherein the metallic material includes aluminum or copper, or the bonding structure includes germanium.
 4. The semiconductor structure of claim 1, wherein a portion of the first substrate is surrounded by the first oxide layer and the conductive or semiconductive material, and the conductive or semiconductive material is isolated from the first substrate by the first oxide layer.
 5. The semiconductor structure of claim 1, wherein the sensing electrode is configured to sense a change of resistance of the sensing material, and the resistance of the sensing material is varied by a chemical reaction between the sensing material and a predetermined material.
 6. The semiconductor structure of claim 1, wherein the heater is extended laterally or vertically along the membrane, or the sensing electrode is extended laterally or vertically over a surface of the membrane.
 7. The semiconductor structure of claim 1, wherein the conductive or semiconductive material includes polysilicon.
 8. The semiconductor structure of claim 1, wherein the membrane includes silicon, silicon dioxide (SiO₂) or silicon nitride (SiN), silicon carbide (SiC), porous silicon or composite film.
 9. The semiconductor structure of claim 1, wherein the sensing electrode includes tungsten alloy, titanium tungsten (TiW), titanium aluminum nitride (TiAlN), tantalum aluminum (TaAl), titanium, titanium nitride (TiN), tantalum, tantalum nitride (TaN), tantalum oxide (TaO), platinum (Pt) or tantalum silicon nitride (TaSiN).
 10. The semiconductor structure of claim 1, wherein the sensing material includes tin dioxide (SnO₂), zine oxide (ZnO) or indium oxide (In₂O₃).
 11. A semiconductor structure, comprising: a CMOS substrate; an intermetallic dielectric (IMD) layer disposed over the CMOS substrate; a bonding structure disposed over the IMD layer; a MEMS substrate including a first surface facing the CMOS substrate and a second surface opposite to the first surface; a metallic material disposed over the first surface; a cavity surrounded by the MEMS substrate; a polysilicon disposed within the MEMS substrate; a first oxide layer disposed between the polysilicon and the MEMS substrate; a second oxide layer disposed over the second surface; a membrane disposed over the second oxide layer and the cavity; a heater disposed within the membrane and electrically connected with the MEMS substrate; a sensing electrode disposed over the membrane and the heater, and electrically connected with the MEMS substrate; and a sensing material covering a portion of the sensing electrode, wherein the CMOS substrate and the MEMS substrate are integrated by bonding the metallic material with the bonding structure and electrically connecting the CMOS substrate with the MEMS substrate.
 12. The semiconductor structure of claim 11, further comprising: an isolation layer disposed over the CMOS substrate and configured to thermally isolate the CMOS substrate from the MEMS substrate; or an interconnect structure including a via portion passing through the isolation layer and contacted with the IMD layer, and an elongated portion extending over and along the isolation layer and configured to receive the bonding structure; or a third oxide layer disposed over the isolation layer and between the via portion and the isolation layer.
 13. The semiconductor structure of claim 11, wherein the bonding structure is a bond pad.
 14. The semiconductor structure of claim 11, wherein the second oxide layer is disposed over the cavity.
 15. The semiconductor structure of claim 11, wherein the heater is configured to provide an operating temperature of about 300° C. to about 800° C. to facilitate sensation of a predetermined gas by the sensing electrode, or the heater has a width of about 0.1 um to about 30 um.
 16. A method of manufacturing a semiconductor structure, comprising: receiving a first substrate including a first surface, a second surface opposite to the first surface, a plurality of vias extending from the second surface towards the first surface and filled with a conductive or semiconductive material, a first oxide layer disposed between the first substrate and the conductive or semiconductive material, and a second oxide layer disposed over the second surface; disposing and patterning a first membrane layer over the second oxide layer; disposing and patterning a heater over the first membrane layer; disposing and patterning a second membrane layer over the heater and the first membrane layer; disposing a sensing electrode over the second membrane layer; disposing a sacrificial oxide over the sensing electrode and the second membrane layer; removing some of the first substrate from the first surface to expose the conductive or semiconductive material; disposing a metallic material over the first surface and the plurality of vias; forming a cavity surrounded by the first substrate; receiving a second substrate including a bonding structure disposed over the second substrate; bonding the metallic material with the bonding structure; removing the sacrificial oxide; and disposing a sensing material over the sensing electrode.
 17. The method of claim 16, wherein the forming the cavity includes etching the first substrate from the first surface to expose the first membrane layer or the second oxide layer.
 18. The method of claim 16, wherein the bonding the metallic material with the bonding structure includes eutectic bonding operations.
 19. The method of claim 16, wherein the removing some of the first substrate includes grinding the first surface towards the second surface.
 20. The method of claim 16, further comprising: forming an intermetallic dielectric (IMD) layer over the second substrate; disposing and patterning an isolation layer over the second substrate; disposing a third oxide layer conformal to the isolation layer; forming an interconnect structure including a via portion contacting with the IMD layer, and an elongated portion disposed along the third oxide layer and coupled with the bonding structure. 